Where to start?

[sortafast]

So I am pretty much a cnc noob. I have had an 8x12 hf lathe for about 4 or 5yrs now and also have a beat up X1 mill that I bought off craigslist for stupid cheap. I now find myself going into business with my wife's cousin making parts for him. Problem is, I will not be able to keep up on my manual lathe , and possibly on the mill as well. So I have me some questions on converting the old 8x to cnc. I see that I need some adaptors to mount the steppers, couplersor belts or something, driver(s) to interface the motors with the computer, a power supply for the motors, some software and a computer with a serial port. I have no clue what to look for in the ball screw department. For kits, there is Xyletex or what ever, they seem fairly reasonable price wise. But I see a lot of folks opting for the gecko drives. What differences or benefits are to be had going with one or the other? I am also wanting to put a 1hp or 3/4hp motor on there with a VFD. Would it be possible to have the computer control the rpms of the lathe motor for the various operations and such? That would make life way easier. As for stepper motors I am assuming the 270oz nema23's would work but the higher torque nema's work better with certain ball screw tpi? Where does everyone get their parts from? Does anyone make an easy one stop shopping conversion kit with everything sans computer? Is there an automatic tool changer on the market that will work on an 8X lathe? I really want to get into the CNC thing as it will open a lot of doors for design and probably save me loads of time. I am just overwhelmed with all the info, and sometimes lack there of, out there and just need to wrap my head around this whole thing. Any help would be much appreciated.

-Dave

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[doorknob]

I understand the feeling of being overwhelmed at this point. My suggestion for getting a handle on the complexity would be to look closely at several other peoples' successful lathe conversions, make a decision about which approach appears to be within your capabilities to duplicate, and then use that one as your pattern. There is no single way to do these conversions, rather there are many approaches that have been successful.

I have a smaller, 7x10 mini lathe that I would like to convert to CNC, however I have also considered the possibility of getting something larger (such as a Grizzly G0602 which is a 10x22 lathe). There are several kits available for the 7x10 (or 7x12 or 7x14) mini lathes, and there are a number of DIY conversions that have been carefully documented as well. By way of contrast, so far it appears that all of the G0602 conversions that I've seen have been DIY ones. The size of your lathe puts it squarely in the middle of that territory.

Can you narrow down the types of operations that you need to automate? For example, for the types of parts that I want to produce on my lathe, I need to do turning and facing and parting operations, and perhaps also center drilling operations, however I have no need or plans to use my lathe for threading of any sort. So for me, that means that I don't need to be concerned about generating or detecting a spindle rotation index signal, or about precisely controlling the motion of the spindle. I can probably get away with manually controlling the spindle rpm to begin with. What operations must your lathe absolutely automate? Can you simplify things to start out by not automating every facet of the lathe's operation?

I don't know of any off-the-shelf automated tool changers for mini lathes - a lot of folks here have built their own turret-style tool changers, based off of a common design. Some people have considered making their own gang tooling attachments.

You can probably hold off from making decisions about the details of the stepper motor controller and the PC until later in the process.

And so on...

[sortafast]

well, the part that we are making will be made out of 4140 and be threaded with 2 different thread sizes separated by a small shoulder. So threading is the main reason for me wanting a conversion. it would simply take too dang long for me to make them in a full scale production environment with the lathe as it is. Plus, having a cnc lathe sitting in the garage really would open up the doors to do other things that I might want to do down the road. I also plan on getting either an X2 or X3 sized mill and doing a conversion on it as well. Between the 2 machines I would be able to do a lot of things that, right now, I would have to pay others to do for me or are so time consuming I won't even bother. For now though, my manual machines will get me by. I just want to save time and energy (my energy anyway) in making these parts.

[doorknob]

OK, then it looks like your CNC lathe requirements are different from mine.

There are several CNC conversions of the G0602 that are being used for threading, and so perhaps those would be good starting places for you to explore.

For example:

http://www.cnczone.com/forums/vertic...he_3_step.html

http://www.cnczone.com/forums/bencht...rsion_why.html

Projects In Metal, LLC » Forum

G0602

and others...

[hoss2006]

Here would be a good place to start.
Attention Newbies! - CNC - The Hossmachine Forum
For an 8x12 cnc DIY conversion you'll be looking at 6 months plus typically to get up and running
depending on your motivation,
Here's a couple good threads on DIY 8X conversions.

http://www.cnczone.com/forums/mini_l..._starting.html

http://www.cnczone.com/forums/mini_l..._slow_mod.html

Have fun, Hoss

[sortafast]

thanks for the links and such, its helped a bunch. So far this seems fairly easy to attain. Just have to figure out how to mount the motors to the lathe and how I want to do the VFD conversion (a whole nother bag of worms in it's own right). Should be fun. I just have to figure out when I am going to do this and how quickly it can be done. I have access to a couple other lathes if I need to if I tore mine down, but I'd rather not go down that road if at all possible.